CN101262816A - Wireless Patient Monitoring Devices for MRI - Google Patents

Abstract

The present invention relates to systems, methods, and related devices for wirelessly transmitting physiological signals or other data in an electromagnetically noisy environment, such as a Magnetic Resonance Imaging (MRI) suite. They allow wireless transmission of data acquired from a sensor module connected to a patient while the patient is within the MR scanner bore. The system includes a first transceiver and a second transceiver. The first transceiver is linked to the sensor module for transmitting data received from the sensor module. A second transceiver, connected to the device remote from the first transceiver, is used to communicate data received from the first transceiver to the device. The first and second transceivers enable one-way or two-way communication between the sensor module and the apparatus while not being adversely affected or adversely affecting the operation of the MR system.

Description

Wireless Patient Monitoring Devices for MRI

Cross References to Applications

This patent application claims priority to U.S. Provisional Application Serial No. 60/489,592, filed July 23, 2003, and entitled "wireless patient monitor device for magnetic resonance imaging." This provisional application has been assigned to the assignee of the invention disclosed hereinafter, and the contents of which are incorporated herein by reference.

technical field

The present invention relates generally to communication systems and methods used during magnetic resonance (MR) imaging and spectroscopy. More particularly, the present invention relates to wireless communication between and/or within various rooms of an MR suite. Still more particularly, the present invention relates to systems and methods for the wireless transmission of physiological data between a patient within the cavity of an MR scanner and monitoring equipment located elsewhere within the MR suite for monitoring the patient and related equipment.

Background technique

The following information is provided to assist the reader in understanding the invention disclosed below and the environment in which it generally applies.

Magnetic resonance imaging (MRI) is a non-invasive method that produces high-quality images of the inside of the human body. It allows medical staff to see inside the human body (such as organs, muscles, nerves, bones and other structures) without using surgery or potentially harmful ionizing radiation (such as X-rays). The resulting images are of high resolution so that diseases and other pathological conditions can often be distinguished from healthy tissue by visual inspection. Nuclear Magnetic Resonance (MR) systems and techniques have also been developed to perform spectroscopic analysis by which the chemical composition of tissue or other materials can be determined.

MR imaging and spectroscopic procedures are performed in the MR suite. As shown in FIG. 1A , an MR suite typically has three rooms: scanner room 1 , control room 2 , and equipment room 3 . The scanner room 1 houses an MR scanner 10 into which the patient is moved via a slidable platform 11 for the scanning procedure, and the control room 2 contains a computer console 20 through which the operator controls the MR system's All operations. In addition to the door 4, a window 5 is usually provided in the wall separating the scanner from the control room to allow the operator to observe the patient during these procedures. The equipment room 3 contains the various subsystems necessary to operate the MR system. The device includes a power gradient controller 31, a radio frequency (RF) assembly 32, a spectrometer 33, and a cooling subsystem 34, which is used to avoid heat build-up which, if left unaddressed, would interfere with the overall MR system performance. These subsystems are usually housed in separate cabinets and like the scanner 10 and the slidable patient platform 11 are also powered through the power distribution panel 12 .

The MR system obtains these detailed images and spectroscopic findings by exploiting the fundamental properties of the hydrogen atom, which has been found to be abundant in all cells of the human body. In human cells, the nuclei of hydrogen atoms spin naturally, or precess randomly, in each direction, like a conch. However, when exposed to a strong magnetic field, the spin axes of the hydrogen nuclei usually align themselves in the direction of that magnetic field. This is because the nucleus of a hydrogen atom has what is known as a large magnetic moment, which is basically an inherent tendency to align itself with the direction of the magnetic field it is in. During an MR scan, the body, or the area in which it is located, is exposed to this magnetic field. This aligns the hydrogen nuclei in the exposed region in the direction of this magnetic field and together form an average magnetization vector.

As shown in Figures IB and 1C, the scanner 10 includes a main magnet 101, three gradient coils 103a-c, and an RF antenna 104 (often referred to as a whole body coil). The main magnet 101 is generally cylindrical and has superconducting properties. Within its cylindrical cavity, the main magnet 101 generates a strong magnetic field, often referred to as B ₀ or the main magnetic field, and is both uniform and static (not changing). In order to perform the scanning procedure, the patient must move into this cylindrical cavity, usually lying supine on a platform 11, as best shown in Figures 1B and 1C. The main magnetic field is oriented along the longitudinal axis of the cavity, known as the z-direction, and it forces the magnetization vectors of the hydrogen nuclei in the body to align themselves in this direction. With this alignment, the hydrogen nuclei are ready to receive RF energy of the appropriate frequency from the RF coil 104 . This frequency is known as the Larmor frequency and is governed by the equation ω=γB ₀ , where ω is the Larmor frequency (the frequency at which hydrogen atoms precess), γ is the gyromagnetic constant, and B ₀ is The strength of the main magnetic field.

The RF coil 104 is typically used to transmit pulses of RF energy and to receive nuclear magnetic resonance (MR) signals induced thereby in hydrogen nuclei. Specifically, during its transmit cycle, the coil 104 broadcasts RF energy into the cylindrical cavity. This RF energy produces a radio frequency magnetic field (also referred to as the RF B ₁ field) with magnetic field lines pointing in a direction perpendicular to the magnetization vector of the hydrogen nuclei. The RF pulse (or B ₁ field) tilts the spin axis of the hydrogen nuclei relative to the main magnetic field (B ₀ ), thereby shifting the net magnetization vector by an angle in the z direction. However, the RF pulse affects only those hydrogen nuclei that precess about their axis at the RF pulse frequency. In other words, only nuclei that "resonate" at that frequency are affected, and this resonance is achieved in conjunction with the operation of the three gradient coils 103a-c.

Each of the three gradient coils is used to linearly vary the main magnetic field (B ₀ ) along only one of the three spatial directions (x, y, z) within the cylindrical cavity. The gradient coils 103a-c are placed inside the main magnet as shown in Figure 1C, and when they are switched on and off rapidly, can change the main magnetic field at a very local level. Thus, in combination with the main magnet 101, the gradient coils can be operated according to various imaging techniques so that at any given point or in any given strip, slice or volume unit, the hydrogen nuclei can be placed under the appropriate conditions. Resonance is achieved when the frequency of the RF pulse. In response to the RF pulse, precessing hydrogen nuclei in the selected region absorb the RF energy emitted from the RF coil 104, thereby forcing their magnetization vectors away from the direction of the main magnetic field ( _B0 ). When the RF coil 104 is turned off, the hydrogen nuclei begin to release their newly absorbed RF energy in the form of nuclear magnetic resonance (MR) signals, as explained further below.

One well-known technique that can be used to acquire images is known as spin echo imaging. Operating according to the MR sequence, the MR system first activates one gradient coil 103a to establish a magnetic field gradient along the z-axis. This is called a "chip select gradient" and it is set up when the RF pulse is applied and turned off when the RF pulse is turned off. It allows resonances to occur only within those hydrogen nuclei located within the slice in the area being imaged. No resonance occurs in any tissue lying on either side of the plane of interest. Immediately after the cessation of the RF pulse, all nuclei in the activated sheet are "in phase", ie their magnetization vectors all point in the same direction. Outside of their own devices, the net magnetization vectors of all hydrogen nuclei in the sheet will "relax" to realign with the z-direction. However, the second gradient coil 103b is briefly activated to generate a magnetic field gradient along the y-axis. This is called a "phase encoding gradient". From the weakest to the strongest end of the gradient within the sheet, it causes the magnetization vectors of the individual nuclei to point in increasingly different directions. Next, after the RF pulse, slice selection gradient and phase encoding gradient have all been turned off, the third gradient coil 103c is briefly activated to generate a gradient along the x-axis. This is called the "frequency encoding gradient" or "readout gradient" because it is only applied when the MR signal is finally measured. It causes the relaxed magnetization vectors to be differentially re-excited, so that nuclei near the low end of the gradient begin to precess at faster rates, while those at the higher end accelerate to greater velocities. When the nuclei relax again, the fastest ones (those at the high end of the gradient) will emit radio waves at the highest frequencies, while the slowest ones emit at the lowest frequencies.

These radio waves are thus spatially encoded by the gradient coils 130a-c such that each portion of the imaging region is uniquely defined in terms of the frequency and phase of its resonant signal. In particular, when the hydrogen nuclei relax, each hydrogen nucleus becomes a tiny radio transmitter, emitting characteristic pulses that vary over time, depending on the local microscopic environment in which the hydrogen nucleus is located. For example, hydrogen nuclei in fat have a different microscopic environment than hydrogen nuclei in water, and therefore pulse differently. Because of these differences, and because different tissues have different water/fat ratios, different tissues emit radio signals at different frequencies. During its receive cycle, the RF coil 104 detects these tiny radio emissions, often collectively referred to as MR signals. From the RF coil 104, these unique resonance signals are passed to the receiver of the MR system, where they are converted into mathematical data. The entire process must be repeated several times to form an image with a good signal-to-noise ratio (SNR). Using a multidimensional Fourier transform, the MR system then converts the above mathematical data into a two-dimensional or even three-dimensional image of the scanned body or an area thereof.

As shown in parts 1A and 1C, the scanner chamber 1 is shielded to prevent the ingress and egress of electromagnetic waves. Specifically, the materials and design of the chamber's ceiling, floor, walls, doors, and windows effectively form a barrier or shield6 against electromagnetic signals (e.g., RF energy) generated during scanning. Leakage outside scanner chamber 1. Similarly, the shield 6 is designed to prevent external electromagnetic noise from entering the scanner chamber 1 . The shield 6 typically consists of copper sheet material or some other suitable conductive layer. However, the window 5 is usually formed by sandwiching a screen material between glass plates, or by coating the window with a thin layer of conductive material, so as to maintain the continuity of the shield. The conductive layer also extends to the door 4, allowing access to the scanner chamber 1 when the door 4 is open, and is grounded to and forms part of the shield 6 when the door 4 is closed. For the typical operating range of an MR scanner (approximately 20-200MHz), the shielding 6 on the roof, floor, doors and walls provides approximately 100dB attenuation, while the shielding on the window 5 provides approximately 80dB attenuation. The barrier 6 thus shields the various critical components of the MR system (e.g., scanner, preamplifier, receiver, local coil, etc.) from sources of undesired electromagnetic radiation (e.g., radio signals present in the local environment). , TV signals and other electromagnetic noise).

The shield 6 is used to prevent external electromagnetic noise from interfering with the operation of the scanner 10, which, if not resolved, may degrade the quality of the images and/or spectroscopic examination results obtained during the scanning process. However, in order for the scanner 10 to operate, the shield 6 must still allow the transfer of data and control signals between the scanner room 1 and the control and equipment rooms 2 and 3, and this transfer is typically through a penetrating panel 16. Achieved.

As shown in FIG. 1A , the penetration plate 16 is generally embedded in the wall between the scanner room 1 and the equipment room 3 . It has several ports through which the scanner 10 and other equipment in the scanner room 1 are connected by cables to the computer console 20 and the control subsystem in the control and equipment rooms 2 and 3 respectively. Each port typically includes a filtered BNC connector that allows the transfer of data and/or control signals while still remaining blocked from unwanted electromagnetic signals.

It is known that several auxiliary systems have been devised for use in MR suites, some of which require communication across isolation barriers. These auxiliary systems are usually bifurcated, ie they have two pieces of equipment, one in the scanner room and the other in the control room. Some MR suites provide or are modified to have multiple penetration plates with additional ports, which have led to the development of divergent systems that take advantage of this additional functionality. In this secondary system, two pieces of equipment on opposite sides of the shield are hardwired with suitable connectors through such ports with RF cables. These ports are tuned and filtered to prevent the passage of frequencies that have the potential to adversely affect the operation of the MR system. Shield, ground, and filter the RF cables in a similar manner to ensure that no external noise couples into the scanner chamber defeating the purpose of the isolation barrier.

Other auxiliary systems use different means to communicate across electromagnetic shielding. One such example is the bifurcated injector system disclosed in U.S. Patent 5,494,036 to Uber III et al., which is incorporated herein by reference. It allows the infusion of contrast medium into the bloodstream of a patient undergoing MR procedures. (Contrast media are used to increase the contrast between different types of tissue in the area of the body being scanned, thereby increasing the resolution of the images obtained during the scanning process). In such a bifurcated system, an injector control unit in the scanner room (with which the contrast medium is injected into the patient's body) communicates with a corresponding controller located in the control room. The '036 patent discloses that the injection control unit and its controller communicate across barriers via a dedicated fiber optic link or a pair of matched transceivers. In a preferred embodiment, the transceivers are attached to opposite sides of the window and are aligned with each other through the window. They allow the infusion control unit and controller to communicate with each other at frequencies that easily penetrate shielding, preferably in the infrared or visible portion of the electromagnetic spectrum, without adversely affecting the operation of the MR system. The injection control unit itself is usually shielded, and any parasitic electromagnetic noise generated by the controller is shielded from affecting the scanner by its isolation within the control room.

US Patent Application Publication 2003/0058502 A1 (incorporated herein by reference) discloses a system for wireless communication across an isolation barrier between two transceivers of a bifurcated equipment system, such as an injection system. The disclosed communication system is shown as an antenna coupling with two antennas, one for communicating with the transceiver on one side of the barrier (the transceiver for the injection control unit) and the other antenna for communicating with the transceiver on the other side of the barrier. The transceiver on the side (transceiver for the controller) communicates.

Although the '036 patent and related technology represent great advances over earlier communication systems for MR environments, there remains a need to develop a communication system that overcomes the inherent shortcomings of this technology. One disadvantage of the system disclosed in the aforementioned '036 patent is that the cables used to connect to the transceivers on either side of the window inevitably limit the mobility of equipment in the scanner room and control room. Although the communication system disclosed in the published application enables mobility of devices on either side of the barrier, the two antennas of its antenna coupling are physically interconnected. Another disadvantage is that antenna coupling is limited to allowing communication across obstructions, thus the need for indoor communication of data or other signals within the MR suite has not been envisioned.

Monitoring vital functions of patients is becoming more and more common in the MR environment. Examples of physiological functions that are often monitored include the oxygen saturation of arterial blood by using pulse oximetry, and the electrical activity of the brain by electroencephalography (EEG). Other electrophysiological signals that can be monitored include electrooculogram (EOG), electroencephalogram (EEG), and electromyography (EMG). Respiration and blood pressure are two other physiological parameters that are routinely monitored, as is the electrical activity of the heart via an electrocardiogram (ECG).

The heart is mainly made of muscle tissue that contracts and relaxes regularly to push blood through the body's circulatory system. The heartbeat begins with a small bundle of nerves in the upper right corner of the right atrium, an area known as the sinoatrial (SA) node or pacemaker. Cells in the SA node generate electrical impulses at regular intervals of about 60-70 times per minute, although those nerves outside the heart can increase or decrease this rate in response to the body's physiological demands and other (chemical) stimuli. These pulses travel through and synchronize the rest of the heart and initiate depolarization and then repolarization of the heart muscle, thereby causing the heart to contract and relax to a regular, steady beat. This depolarization spreads out in waves, cell by cell, through the myocardium and certain nerve fibers of the heart. Once depolarization is complete, heart cells are able to regain their resting polarity through a process called repolarization. , the electrical activity of the heart can be detected by electrodes added to the skin through the conductive tissue on the body surface. Typically, a small amount of conductive gel is applied to the skin, which makes it easier to transmit the signal to the electrodes. Each electrode typically has metal prongs or connection points to which the conductive leads are connected by corresponding clips. Each lead carries the bioelectric signal voltage from its corresponding electrode to an electrocardiogram or other suitable monitoring device. The resulting cardiac signal is derived from the measured voltage difference between two such electrodes as a function of time. In an image called an electrocardiogram or signal (ECG), the heart signal appears as clusters of peaks and troughs. For basic ECG monitoring, a 3-wire lead set is typically used. However, if more detail (eg, details about the different phases of the heartbeat) is required to more likely detect a wider range of cardiac abnormalities, then a lead set with a higher number of leads/electrodes may be used.

However, physiological monitoring in an MR suite is complicated by the electromagnetic environment within the scanner room. This is because conductive wires are commonly used to communicate physiological data in the form of signal voltages from the patient to monitoring equipment. The RF pulses and changing magnetic fields generated during MR scans tend to induce parasitic electrical noise in such wires, which appears as artifacts in the signal voltage. Electronic devices commonly found in MR suites, such as fans and lights, also emit electromagnetic emissions that can induce noise in the wires. Additionally, any movement of the wires in the magnetic field tends to cause artifacts in the signal voltage. In addition to these noise and motion artifacts, the RF pulses from the scanner, depending on their strength, can generate currents of sufficient magnitude to cause heating of the wires, which puts the patient at risk of burns.

The 9500 Multi-Gas Monitor, manufactured by Medrad Inc. of Indianola, Pennsylvania, uses a fiber optic link between the sensor device (which connects to the patient inside the scanner cavity) and the monitor (which is located elsewhere in the MR suite, usually a Transmit ECG and pulse oximetry data between in the scanner room). This is described in US Patent 6,052,614 to Morris, Sr. et al., which is incorporated herein by reference. Fiber optic cables are somewhat immune to noise and motion artifacts, and also reduce the amount of noise radiated by monitoring equipment that can adversely affect images produced by MR systems. The fiber optic cable also isolates the patient from the RF energy generated by the scanner, eliminating the risk of burns or shocks that can occur when using conductive cables. The disadvantages of this system are the same as those of the cable-related equipment described above, the fiber optic cables not only obstruct the operators in the scanner room, but also limit the mobility and placement of the monitors in the MR suite.

In addition, there are bifurcated systems such as the Magnitude ^™ patient monitor made by Invivo Research Inc. and the infusion system made by Medtron Medical Systems Inc. (Saarbrucken, Germany), whose communication systems use high-frequency RF signals to penetrate shielding, Transfer between scanner room and control room. These products, however, still rely on cables to connect sensor devices on the patient inside the scanner cavity to corresponding monitors outside the cavity. Therefore, it would be desirable to have a wireless connection between the sensor device (located within the cavity) and the corresponding monitoring device (located within the scanner or control room). This wireless connection can also be used to couple signals from the patient's sensor device to the MR system (eg ECG signals which can be used to trigger scanner operation at appropriate points during the cardiac cycle to obtain cardiac images).

Contents of the invention

Several objects and advantages of the invention are achieved by the various embodiments and related aspects of the invention summarized below.

In a presently preferred embodiment, the present invention provides a system for the wireless transmission of physiological data indicative of the condition of a patient exposed to an MR system scanner. The system includes a sensor mechanism, a first transducer circuit, a first RF transceiver circuit, a second RF transceiver circuit, and a second transducer circuit. The sensor mechanism is used to acquire physiological data from the patient. A first transducer circuit is connected to the sensor mechanism to convert physiological data received from the sensor mechanism from optical to electrical form. A first RF transceiver circuit is connected to the first transducer circuit for transmitting physiological data received from the first transducer circuit. A second RF transceiver circuit remote from the first RF transceiver circuit is used to receive physiological data transmitted by the first RF transceiver circuit. The second transducer circuit is connected to the second RF transceiver circuit to convert the physiological data received from the second RF transceiver circuit from electrical form to optical form and transmit the physiological data to a device remote from the sensor mechanism . Communication between the sensor mechanism and the device is achieved through the first and second RF transceiver circuits without adversely affecting or being adversely affected by the operation of the MR system.

In a related embodiment, the present invention provides a system for wirelessly transmitting data in an environment with electromagnetic noise. The system includes a first transducer circuit, a first RF transceiver circuit, a second RF transceiver circuit, and a second transducer circuit. A first transducer circuit is connected to the first device of the bifurcated system to convert data received from the first device from optical to electrical form. A first RF transceiver circuit is connected to the first transducer circuit for transmitting data received from the first transducer circuit. A second RF transceiver circuit remote from the first RF transceiver circuit is used to receive data transmitted by the first RF transceiver circuit. The second transducer circuit is connected to the second RF transceiver circuit to convert data received from the second RF transceiver circuit from electrical form to optical form and to communicate the data to the second device of the bifurcated system . The communication scheme used by the first and second RF transceivers enables the first and second devices to communicate without being adversely affected by ambient noise.

In another related embodiment, the present invention provides a system for wirelessly transmitting data in an MR suite. The system includes a first transceiver circuit and a second transceiver circuit. The first transceiver circuit is connected to the sensor module to transmit data received from the sensor module and to pass data transmitted to the first transceiver circuit to the sensor module. A second transceiver circuit connected to the monitoring device is used to communicate data received from the first transceiver circuit to the monitoring device and to communicate data received from the monitoring device to the first transceiver circuit. The first and second transceiver circuits communicate using a predetermined frequency outside the operating range of the device within the MR suite without adversely affecting the operation of the device.

In a different embodiment, the present invention provides a system for wireless transmission of data obtained by sensor modules attached to a patient in an imaging scanner. The system includes a first transceiver and a second transceiver. A first transceiver is linked to the sensor module for transmitting data received from the sensor module. A second transceiver connected to the device remote from the first transceiver is used to communicate data received from the first transceiver to the device. The first and second transceivers enable the sensor module and the device to communicate without adversely affecting the operation of the imaging scanner and, in turn, without adversely affecting the imaging scanner.

The present invention also provides a method of wirelessly transmitting data indicative of at least a condition of a patient exposed to a scanner of an MR system. The method includes: acquiring data from a sensor mechanism connected to a patient; and converting the data from an optical form to an electrical form. It also requires: transmitting the data received electrically in radio frequency (RF); and then, receiving the data transmitted in the transmitting step. The method also includes: converting the data received in the receiving step from an electrical form to an optical form; and communicating the data to a device remote from the patient. The method requires data communication to be achieved without adversely affecting the operation of the MR system and at the same time without adversely affecting the operation of the MR system.

In a related aspect, the present invention also provides a method of wirelessly transmitting data in an imaging suite. The method comprises the steps of providing a first transceiver connected to the sensor for transmitting data received from the sensor and for communicating data transmitted to the first transceiver to the sensor. It also includes the steps of: providing a second transceiver connected to a device remote from the first transceiver to communicate data received from the first transceiver to and from the device The received data is sent to the first transceiver. The method requires that the first and second transceivers communicate without adversely affecting, and without adversely affecting, the operation of equipment in the imaging suite.

In a presently preferred embodiment, the present invention provides a communication module for wireless transmission of electrocardiogram (ECG) signals obtained from a patient located in a noisy environment. The module includes at least one RF filter, lead selection network, differential amplifier, amplifier circuit, signal processing circuit, modulator circuit, transmitter circuit, and filter circuit. RF filters are linked to the sensors of the bioelectrical signals in order to remove frequencies from the bioelectrical signals other than those used to carry these bioelectrical signals. The lead selection network is used to select the appropriate lead from the multi-lead lead set (from which the selected one of the bioelectrical signals is picked up) in response to the control signal. A differential amplifier is used to derive the ECG signal from the network-selected bioelectrical signal. An amplifier circuit is used to amplify the ECG signal received from the differential amplifier, and a signal processing circuit is used to condition the ECG signal received from the amplifier circuit. The modulator circuit digitally modulates the carrier signal based on the ECG signal it receives from the signal processing circuit to form a modulated signal. The transmitter circuit is connected to the modulator circuit for transmitting the modulated signal received from the modulator circuit. A filter circuit connected to the transmitter circuit allows this modulated signal to pass while effectively attenuating unwanted frequencies.

In a related embodiment, the present invention also provides a communication module for wireless transmission of physiological signals obtained from a patient located in a noisy environment. The module includes input conditioning circuitry, signal processing circuitry, converter circuitry, transmitter circuitry, and filter circuitry. An input conditioning circuit of a sensor linked to the physiological signal is used to adapt the physiological signal received from the sensor to the module. The signal processing circuit improves the condition of the physiological signal received from the input conditioning circuit, and the converter circuit converts the physiological signal received from the signal processing circuit into a corresponding digital signal. The transmitter circuit is connected to the converter circuit and is used to transmit the digital signal received from the converter circuit. A filter circuit is connected to the transmitter circuit to pass the digital signal and effectively attenuate unwanted frequencies.

Description of drawings

The invention and its various embodiments will be better understood with reference to the following detailed description and accompanying drawings, in which:

Figures 1A, 1B, and 1C show the layout of the MR suite, which includes the scanner room where the scanner and patient platform are located, the control room where the computer console that controls the scanner is located, and the various control subsections for the scanner. The equipment compartment where the system is located;

Figure 2 is a first preferred embodiment of a system for wirelessly transmitting ECG data between a patient placed in an MR suite and monitoring equipment;

Figure 3 is a second preferred embodiment of a system for wirelessly transmitting ECG data between a patient placed in an MR suite and monitoring equipment;

4 is a block diagram of a preferred embodiment of a wireless ECG sensor module of the type shown in FIGS. 2 and 3;

Figure 5 is a block diagram of a preferred embodiment of a wireless patient sensor module capable of transmitting substantially any type of data between a patient placed in an MR suite and monitoring equipment;

6 is a schematic diagram of a transceiver assembly for converting physiological data obtained from a patient sensor module from optical signals to RF signals according to a second preferred embodiment of the present invention;

7 is a schematic diagram of transceiver components for converting physiological data received as RF signals back into optical signals in accordance with a second preferred embodiment of the present invention.

Detailed ways

Although the present invention is described and illustrated herein primarily in the context of systems and methods for wireless transmission of physiological data in or around an MR environment, the reader will understand that the present invention is not only applicable or applicable to other types of data , can also be applied or adapted to various other environments. Various embodiments and related aspects of the invention will now be described with reference to the drawings, wherein like elements are designated by like numerals where possible.

2-7 illustrate several embodiments of the present invention, namely systems, methods and related devices for wireless transmission of physiological signals or other data in an electromagnetic noise environment. More specifically, these figures illustrate a system for bidirectional or unidirectional data transmission between a patient within the cavity of an MR scanner and corresponding monitoring equipment located elsewhere in the MR suite. As will be apparent from the various embodiments disclosed below, the present invention is best implemented through RF communication techniques, but may also be implemented using optical communication schemes. RF communication schemes are preferred since line of sight limitations are no longer a serious problem. It is preferable to transmit physiological data out of the cavity using RF signals in the microwave region, since the cavity can effectively act as a waveguide for RF signals with a cutoff frequency in the lower frequency range (less than 500 MHz).

FIG. 2 shows a first embodiment of a system, indicated generally at 100 , for wireless communication between an ECG module 110 and a monitor 150 located elsewhere in an MR suite. ECG module 110 and monitor 150 each include a transceiver and associated antenna to enable communication between the two, preferably bidirectionally. In this particular depiction, ECG module 110 includes an integrated transceiver and antenna assembly 710 , just like monitor 150 with transceiver and antenna assembly 750 . The design of the ECG module 110 and its transceiver assembly 710 allows for use with the patient even when the patient is exposed to the electromagnetic noise environment within the cavity of the MR scanner. As described in detail below, this design therefore requires that a communication scheme be used that not only ensures reliable communication between the ECG module 110 and the monitor 150, but also avoids interference with surrounding MR systems using the communication scheme.

FIG. 3 shows a second embodiment of a system, indicated generally at 200 , for wireless communication between an ECG module 110 and a remotely located monitor 150 . Although similar to the embodiment shown in FIG. 1 , this embodiment uses a transceiver assembly 720 that is not integral to the ECG module 110 . More specifically, ECG module 110 and transceiver assembly 720 are connected by fiber optic communication link 725 rather than the more direct connection of FIG. 2 . The communication link 725 is preferably implemented using the communication scheme presented below in conjunction with FIGS. 6 and 7 .

6 and 7 show schematic circuit diagrams of two transceiver assemblies that can be used or adapted in various embodiments of the present invention. Together, these transceiver assemblies serve as the central part of a system that can be used to wirelessly transmit data between a sensor module on a patient and a remotely located monitoring device (broadly, between any two devices in a bifurcated system). In a presently preferred embodiment, the system (generally indicated at 300) includes a sensor mechanism 310, a first transducer circuit 320, a first RF transceiver circuit 330, a second RF transceiver circuit 340, a second A transducer circuit 350, and two power regulation circuits 370. One or both transceiver components of system 300 may also optionally have a link status indicator circuit 380 .

The sensor mechanism 310 of the system 300 may utilize any of several prior art electrode/lead set assemblies that are used to conduct electrical current from the surface of living tissue. Especially when the system 300 is used in a noisy environment such as in a typical MR suite (e.g., the sensor mechanism 310 is located within the scanner cavity), provision should be made so that the The bioelectrical signal should be accompanied by as little noise as possible. Although sensor mechanism 310 is presented herein in the context of an ECG module designed for use in an MR suite, it should be apparent that sensor mechanism 310 could also be implemented in other forms such as EEG modules, EMG modules, or even EOG modules. However implemented, sensor mechanism 310 is a device used to acquire data indicative of a patient's condition. In a preferred embodiment, the sensor mechanism 310 can also be enabled to communicate data about its operating status, and the sensor mechanism 310 can also be enabled to act upon receipt of a control signal. This data is intended to be transmitted to a remotely located monitoring device 360 for the purpose of visual display, audio alert, or other appropriate action. Two preferred embodiments of the communication module, one specific to the ECG environment and the other general purpose, which may at least partially include the sensor mechanism 310, are disclosed below in conjunction with FIGS. 4 and 5 .

The first transducer circuit 320 is used to convert data received from the sensor mechanism 310 from optical to electrical form. Such optoelectronic transducers may take the form of the HFBR-2523 Fiber Optic (FO) Transceiver manufactured by Agilent Technologies Inc. As disclosed in Agilent publication 5988-1765EN (incorporated herein by reference), the HFBR-2523 FO transceiver provides high immunity to interference from electromagnetic interference (EMI) sources and radio frequency interference (RFI) sources. As a result, the HFBR-2523 transceiver is well suited for noisy environments like those found in MR suites. As shown in FIG. 6, pin 3 of the HFBR-2523 transceiver is connected to a power regulator circuit 370 to receive 5V DC from the power regulator circuit 370, while pin 2 is grounded. The HFBR-2523 transceiver receives optical data from the sensor mechanism 310 . The electrical data output by the HFBR-2523 FO transceiver is output through pins 1 and 4, which provide the electrical data to the input of the first RF transceiver circuit 330.

The first RF transceiver circuit 330 is connected to the first transducer circuit 320 and is used to transmit data received from the first transducer circuit 320 . It includes a transceiver module 331 , a filter 337 and an antenna 339 . Transceiver module 331 may be implemented in the form of a TR-916-SC-PA RF transceiver module sold by Linx Technologies Inc. As shown in Figure 6, and as described in "SC-PA SERIES TRANSCEIVER MODULE DESIGN GUIDE" ("SC-PA Series Transceiver Module Design Guide", cited here as a reference) published by Linx Corporation, TR- The 916-SC-PA module receives electrical data signals output from pins 1 and 4 of the HFBR-2523 FO transceiver at its TXDATA end. When switching to transmit mode by applying high logic level and low logic level to TXEN terminal and RXEN terminal respectively, and by biasing the PDN pin to open, the TR-916-SC-PA module transmits from its ANT pin The frequency modulated signal is sent out in the frequency modulated signal, and the data signal applied to the TXDATA pin is carried on the frequency modulated signal. The TR-916-SC-PA module 331 is capable of transmitting modulated signals centered at 916.48MHz at data rates up to 33.6Kbps.

Filter 337 is preferably implemented as a TKS2606CT-ND dielectric filter manufactured by Toko Inc. The TKS2606CT-ND filter has a center frequency of 915MHz and a bandwidth of ±13.0MHz as disclosed in data sheet (T042)749 (herein incorporated by reference). When its input is connected to the ANT terminal of the transceiver module 331 , the filter 337 will effectively remove unwanted signals and spurious noise, while allowing the modulated signal it receives to pass to the antenna 339 . Although the TKS2606CT-ND model is a band-pass filter, high-pass and notch filters can also be used to attenuate frequencies other than those carrying relevant data.

The antenna 339 of the first RF transceiver circuit 330 may take the form of any number of commercially available antennas. An example of an acceptable antenna is the ANT-916-CW-QW antenna manufactured by Linx Technologies Inc. This type of antenna can also be used as the antenna 349 of the second RF transceiver circuit 340 .

The second RF transceiver circuit 340 configured to receive data transmitted by the first RF transceiver circuit 330 through the antenna 339 includes: a transceiver module 341 , a filter 347 and an antenna 349 . The modulated signal radiated by the antenna 339 of the first transceiver circuit 330 is initially received by the antenna 349 and then passed to the filter 347 . Like its counterpart in the first transceiver circuit, filter 347 may be implemented as a TKS2606CT-ND bandpass filter, or as a low-pass, high-pass or notch filter. The filtered modulation signal output by the filter 347 is passed to the ANT terminal of the transceiver module 341 .

Like transceiver module 331, transceiver module 341 may be implemented in the form of a TR-916-SC-PA RF transceiver unit. When switching to receiving mode by applying low logic level and high logic level to TXEN terminal and RXEN terminal respectively, and by turning on PDN terminal, TR-916-SC-PA module can receive at its ANT pin An RF transceiver circuit 330 transmits a frequency modulated signal. Then, the TR-916-SC-PA module 341 demodulates the modulated signal, and transmits the resulting data signal to the second transducer circuit 350 through its RXDATA terminal.

The second transducer circuit 350 is used to convert the electrical data signal it receives from the transceiver module 341 into optical form. It includes a drive circuit 351 and an electro-optic transducer 357 . Especially when one expects to interconnect the transducer 357 and the remote device 360 with a very long fiber optic cable, the driving circuit is mainly used to ensure that there is enough power to drive the electro-optical transducer 357 . The driver circuit 351 may be embodied as an N-channel MOSFET, such as the VN2222L chip disclosed in document 70213 S-04279-Rev.F by Vishay Intertechnology Inc., published July 16, 2001. The electro-optic transducer 357 can be the HFBR-1523 FO transceiver manufactured by Agilent Technologies Inc., which is disclosed in Agilent bulletin 5988-1765EN. As shown in FIG. 7 , the gate of the MOSFET receives the electrical data signal from the RXDATA terminal of the transceiver module 341 . The source and drain terminals of the drive circuit 351 provide the amplified electrical output to terminals 2 and 4 of the HFBR-1523 FO transceiver. The optical data signal output by the HFBR-1523 FO transceiver is then routed to the remote device 360 via a fiber optic cable or other suitable waveguide.

Regulator stage 490 may be implemented with any type of regulator circuit known in the electrical/electronic arts. For example, the regulator shown in Figure 6A is a precision voltage reference model REF02 manufactured and sold by Analog Devices Inc. of Norwood, MA. As disclosed in its specification sheet Rev. C (2002) (incorporated herein by reference), the REF02 regulator 490 is capable of providing stable regulation to varying is about ±1% of the 5V DC output. The 5V DC reference voltage is provided to the output selector stage 410 and the indicator stage 480 .

Power regulation circuitry 370 for each transceiver component in system 300 may take the form of any of a variety of regulator circuits known in the electrical/electronic arts. One such regulator is the LM7805 regulator produced by Fairchild Semiconductor Inc. As disclosed in the MC78XX/LM78XX/MC78XXA data sheet dated July 2, 2001 (herein incorporated by reference), the LM7805 regulator is capable of providing a regulated 5V DC output from a 9V DC input. The first transceiver assembly has a regulation circuit 370 with which a 5V DC reference voltage is provided to the HFBR-2523 FO transceiver 320 and the TR-916-SC-PA transceiver module 331. Similarly, other transceiver components have a regulation circuit 370 for providing a 5V DC reference voltage to the driver circuit 351, HFBR-1523 FO transceiver 357, and TR-916-SC-PA transceiver module 341.

The link status indicator circuit 380 of the system 300, which is preferably only embedded in the second transceiver circuit 340, can be implemented with an N-channel MOSFET (such as a VN2222L chip) and a light emitting diode (LED). As shown in FIG. 7, the LED has its anode connected to the 5V DC voltage provided by the regulating circuit 370, and its cathode connected to the drain of the MOSFET. The gate of the MOSFET is connected to the RSSI ("Received Signal Strength Indicator") terminal of the transceiver module 341, from which the MOSFET receives a bias signal when the module 341 is transmitting or receiving. When so biased at its gate, the MOSFET is turned on, thereby connecting its drain to the source and thus providing a path to ground to power the LED. The primary purpose of the indicator circuit 380 is to provide a visual indication to the user when data is being transferred between the sensor mechanism 310 and the remote device 360 .

The data transmitted by the sensor mechanism 310 need not be limited to only physiological data. It may also include data about the operation and status of the sensor mechanism 310 itself. Examples of the types of operational data that may be transmitted include the following information: (i) the state of charge of the battery powering the conditioning circuit 370, and, if applicable, (ii) from which of the multi-lead lead sets the underlying physiological signal is derived. Or which few leads are obtained.

Although the above has focused on a one-way communication scheme, the system 300 is also capable of two-way communication. The two transducer circuits 320 and 350, the two TR-916-SC-PA transceiver modules 331 and 341, and the two filters 337 and 347 are all designed for two-way communication. As a result, the present invention is also capable of transmitting data from remote device 360 to sensor mechanism 310 . Examples of the types of data that may be transmitted back to sensor mechanism 310 include control signals. Such a control signal may be used to command the sensor mechanism 310 to select only certain leads of a multi-lead lead set from which to pick up the underlying sample signal. In the case of an ECG (e.g., where a 3-lead lead set is used), the control signal may instruct the sensor mechanism 310 to select two of those 3 leads to pick up the physiological signal from This transmits the ECG signal obtained from those two physiological signals.

The present invention also contemplates a method of wirelessly transmitting data such as physiological signals indicative of the condition of a patient exposed to an MR system scanner. In a presently preferred embodiment, the method includes: acquiring data from a sensor module (eg, ECG module 110 ) attached to the patient; and converting the data from optical to electrical form. The electrical data signal is then transmitted in RF form by a first transceiver assembly associated with the sensor module. The method also includes the steps of: using a second transceiver assembly remote from the sensor module to receive the RF data signal transmitted by the first transceiver assembly; and then converting the data from electrical to optical form. The optical data signal is then passed from the second transceiver assembly to a remote setting device (eg, monitor 150 ) linked thereto.

Additionally, the method preferably enables communication from the remote device to the sensor module. In the presently preferred embodiment, this includes: converting data received from the remote device from optical to electrical form; transmitting the electrical data signal to the second transceiver assembly; and transmitting it in RF form to the first receiver component. The following steps include: using the first transceiver assembly to receive the transmitted RF data signal; and then converting the data signal from electrical form to optical form for delivery to and use by the sensor module. Examples of the types of data that may be transmitted back to the sensor module include the control signals described above in connection with the preferred system embodiment. [[As described more fully below, the communication between the sensor module and the remote device must be accomplished without adversely affecting, and without adversely affecting, the operation of the MR system]].

The present invention also provides two preferred implementations of communication modules - one ECG specific and the other general purpose - capable of communicating with remotely located monitoring devices 150/360. Figure 4 shows a communication module suitable for use with an ECG electrode/lead set assembly to facilitate wireless transmission of ECG signals obtained from a patient in a noisy environment such as within a scanner cavity. In its preferred embodiment, the communication module (generally indicated at 800) includes an RF filter 805, lead selection network 810, differential amplifier 815, amplifier circuit 820, signal processing circuit 825, modulator circuit 830, transmitter circuit 840 , filter circuit 850 and antenna 855 . The RF filter 805 is linked to the ECG electrode/lead set sensor from which it receives the bioelectrical signal from each lead. The filter is adjusted to remove frequencies other than those transmitting the bioelectrical signal. In response to a control signal sent from the remote device 150/360, the lead selection network 810 is used to select a particular lead in the electrode/lead set sensor from which the bioelectric signal can be picked up. The differential amplifier 815 obtains the ECG signal from the bioelectrical signal selected by the network 810 . Amplifier circuit 820 is used to amplify the ECG signal received from the differential amplifier. Signal processing circuit 825 is preferably used to improve the condition of the ECG signal received from the amplifier circuit. The modulator circuit 830 digitally modulates the carrier signal according to the ECG signal received from the signal processing circuit to form a modulated signal. A transmitter circuit 840, preferably configured to transmit in the microwave band, is coupled to the modulator circuit for transmitting a modulated signal received from the modulator circuit. Filter circuit 850 passes the modulated signal received from the transmitter circuit, but attenuates extra noise and other unwanted frequencies. The modulated signal is then radiated by a suitable antenna.

To enable two-way communication, the communication module may also include a limiter circuit 860 , a receiver circuit 870 and an encoder circuit 880 . A limiter circuit 860 is linked to the filter circuit 850 in order to limit the amplitude of the control signal picked up by the antenna from the remote device 150/360. The receiver circuit 870 is connected to the limiter circuit from which the control signal is received. Optionally in response to the control signal, encoder circuit 880 may be used to encode an output ECG signal having information regarding various operating parameters. Examples of these parameters include the following information: the amount of power available to the communication module; and the particular lead in the electrode/lead set sensor from which the bioelectric signal is picked up.

Figure 5 shows a communication module suitable for a more general form of patient sensor, such as an EEG module, EMG module, or even an EOG module. Such a communication module 900 includes an input conditioning circuit 910 , a signal processing circuit 920 , a converter circuit 930 , a transmitter circuit 940 , a filter circuit 950 , a limiter circuit 960 , a receiver circuit 970 and a control circuit 980 . Collectively, such circuitry performs largely the same functions as those described in connection with communication module 800, while making appropriate adjustments to accommodate different types of patient sensors that may be used therewith.

In addition to signal acquisition and processing circuitry, communication modules 800 and 900 preferably include a means for ensuring the integrity of communications between itself and the remote device with which it communicates. For example, the communication module may use a CRC (Cyclic Redundancy Check) or similar verification test to determine the bit error rate in communication transmissions between itself and the remote device.

In the various disclosed embodiments, the transfer of data must be accomplished without adversely affecting, and without adversely affecting, the operation of the device in the environment in which the communication occurs. For example, when used in an MR suite, the transceiver assembly and communication module disclosed herein must include features for reducing the noise in the image due to RF noise within the sensitive listening region (near the Larmor frequency) of the scanner's electromagnetic spectrum. devices that exhibit the possibility of artifacts. Otherwise, this noise can cause artifacts in the images obtained during scanning. Transceiver components and communication modules must also be protected from high-energy RF signals radiating from the scanner while scanning is in progress. By using the industrial, scientific and medical (ISM) communication bandwidths of 915MHz, 2.4GHz and 5.8GHz, microwave communication can be performed without applying for a license. Additionally, other licensed microwave frequency bands may also be used, such as those discussed in the aforementioned US Patent Application Publication 2003/0058502 Al. At these higher frequencies, smaller antennas can be used, which will beneficially reduce the RF signal energy received from the scanner, since the length of the antenna is much less than λ/10 relative to the scanner wavelength used . As with any type of device inside the scanner cavity, the antenna and all other electronic components should be constructed of non-magnetic materials. Shielding should also be used to further reduce the susceptibility of the communication module to electromagnetic energy emitted by the scanner.

For communication schemes using microwave frequencies such as in the 2.4GHz ISM band (e.g., 802.11b, Bluetooth ^™ ), filters can be constructed as microstripline filters, waveguide filters, surface acoustic wave (SAW) filters, or dielectric filters. (An example of a dielectric filter that works well at 2.4GHz is from Toko Inc., model TFM1B-2450T-10. This device has a center frequency of 2.450GHz, a passband width of 50MHz, and a maximum passband insertion loss of 2.3 dB.) may also use ultra-wideband (UWB) technology, which was recently approved by the Federal Communications Commission (FCC). UWB radio systems typically use pulse modulation, whereby extremely narrow pulses are modulated and transmitted in order to transmit or receive information. Transmit bandwidth typically exceeds one gigahertz. In some cases, "impulse" transmitters are used, where the pulse does not modulate the carrier. Instead, the radio frequency emission generated by the pulse is applied to the antenna, and the resonant frequency of the antenna determines the center frequency of the radiated emission. The bandwidth characteristics of the antenna will act as a low-pass filter, further affecting the shape of the radiated signal.

The high-frequency signals used for this communication are substantially above the Larmor frequency of the scanner and are therefore less likely to cause interference with or be affected by the MR system. A high-pass filter with a cutoff frequency above the Larmor frequency and sufficient stop-band attenuation (e.g., 80 to 100 dB of signal loss) will allow the data signal to pass but reduce any potential interference with the MR scan or image generation Artifacts of low-frequency signals.

To protect the electronics, the communications module 800/900 includes a limiter circuit 860/960 to block any excess RF energy from coupling from the scanner to the antenna. It is best to use a device such as a PIN-PIN diode limiter or a PIN-Schottky diode limiter to prevent RF energy from being coupled from the scanner to the antenna above a certain limit (typically about 10dBm), but when transmitting physiological data Allow enough energy to pass through. A microwave PIN diode is a current-controlled semiconductor device that acts as a variable resistor at RF and microwave frequencies. When a device is used as a shunt on an antenna input, it can effectively limit incoming signals when they become excessive. A combination of two PIN diodes can be used for receiver input protection and as an antenna transmit-receive switch (ie, they can be used in a circuit that isolates the receiver from the transmitter while the transmitter is operating).

During scanning, it is also possible to transmit data signals from the communication module for brief periods when the scanner's RF signals or gradient coils are not used. This results in less noise and more reliable communication. For ECG applications, "non-runtime" window inspection of the scanner can be performed by monitoring the leads of the electrode/lead set assembly for signatures of the RF and gradient sensing signals from the scanner.

For system 100 shown in FIG. 2, ECG module 110 is connected by a fiber optic link to transceiver assembly 710, which may be located near or on the patient platform or on the surface of the scanner housing. This approach allows the use of non-microwave RF signals for communication. In addition, this approach allows greater flexibility in the placement of monitoring equipment (eg, displays) because non-microwave RF signals are not directional. This approach also offers the added advantage of potentially using a separate, larger battery power source for the transceiver, allowing the system to communicate over longer distances and run longer. Note that by converting optical or electrical signals into RF signals by some modulating means, it is possible to replace the currently used fiber optic or wire connections with wireless connections. For battery powered devices, pulse position modulation or other high power efficient modulation schemes are preferred.

To maximize flexibility in device placement, the antennas described herein are preferably circularly polarized, such as by using a helical antenna design to achieve this. Although each antenna may lose a nominal 3dB of gain, this allows greater flexibility in the orientation, polarization, and placement of the antennas on the communications equipment. If the transceiver assembly/communication module is likely to be located at a fixed location in the operating environment, an antenna design with greater gain/better directivity (such as a parabolic antenna design, horn antenna design, or Yagi antenna design) can be used to thereby Optimum signal strength coupling and system signal-to-noise ratio (SNR).

Additionally, it is possible to use broadband antennas operating at multiple frequency octaves to allow communication at several frequencies. For example, helical antenna designs are broadband by nature and can be used to operate in more than one frequency range. Multiple antennas can also be used for antenna diversity, which is a way of dealing with the effects of multiple signal transmissions, especially in scanner rooms, which are likely to be highly reflective environments due to metal shielding and the equipment often located within them. Any directional antennas used to increase signal gain are best placed in the control room, where multipath effects are likely to be less than in the scanner room.

For the transceiver assembly 710/720 and the communication module 800, it is possible to use the leads of the electrode/lead set assembly as an antenna. The antenna can be realized as an additional conductor with a lead set. Alternatively, wires that are part of a lead set can be used. Appropriate band stop filtering must be included to eliminate the input of RF energy from the scanner but allow output of higher frequency signals for RF communications. If the lead set assembly is to be used as an antenna, the leads must be of the proper length and must be properly tuned to ensure they are effective antennas. Additionally, the RF transmit power from the transceiver assembly/communication module must be limited to safe levels.

Because the transceiver assembly/communication module is battery powered, some power management is available to help maintain the operating time of these devices. This can be accomplished in many ways. First, the transceiver assembly/module can be enabled to monitor when a data signal is received from a remotely located transceiver. When a data signal is received, the rest of the system can be powered up. If the signal from a device located outside the scanner cavity is absent for a certain period of time, the rest of the system can be powered down. Second, the transceiver assembly/module can monitor for motion and power up for a certain period of time after motion is detected. Finally, the transceiver component/module can monitor the RF energy from the scanner, indicating that the scanner is running and powered up for a certain period of time. Additionally, as part of power management, the transceiver assembly/module may issue a low battery voltage warning, or send data at a reduced rate to indicate that the battery voltage is low, while extending the remaining battery duty cycle.

The wireless links disclosed herein may have other uses besides monitoring physiological data. For example, wireless technology can also be used to control infusion devices connected to patients. For example, it can be used to program, start or end the injection process, and transfer injection status to another device. Another potential application is controlling adjustable body coils for MRI, such as head and neck coils used to measure the temporomandibular joint (TMJ). The concepts of the present invention are also applicable to bifurcated systems of the type used to monitor patient response in practical MRI studies. Similarly, the present invention is equally applicable to systems (eg, headsets or video devices) capable of providing wireless video and/or sound to and from a patient.

According to the patent laws, the preferred and alternative embodiments for carrying out the invention have been described in detail. Those of ordinary skill in the art to which the invention relates will recognize that there are many alternative ways of practicing the invention without departing from the spirit of the following claims. Consequently, all changes and modifications that fall within the literal meaning of the claims or within the range of equivalents thereof are to be embraced in the scope of the claims. Those skilled in the art will also appreciate that the scope of the invention is indicated by the claims and not limited by any particular example or embodiment discussed or illustrated above.

Therefore, in order to promote the progress of science and practical technology, I use the patent certificate to secure the exclusive right to all the subject matter covered by the claims within the time stipulated by the patent law.

Claims (38)

1. A system for wirelessly transmitting physiological data representing the condition of a patient exposed to a magnetic resonance (MR) system scanner, the system comprising: (a) a sensor mechanism for obtaining said physiological data from said patient; (b) a first transducer circuit connected to said sensor mechanism for converting said physiological data received from said sensor mechanism from an optical form to an electrical form; (c) a first RF transceiver circuit connected to said first transducer circuit for transmitting said physiological data received from said first transducer circuit; (d) a second RF transceiver circuit remote from the first RF transceiver circuit and configured to receive the physiological data transmitted by the first RF transceiver circuit; and (e) a second transducer circuit connected to said second RF transceiver circuit for converting said physiological data received from said second RF transceiver circuit from an electrical converting form to optical form and communicating said physiological data to a device remote from said sensor mechanism; wherein the communication between the sensor mechanism and the device via the first and second RF transceiver circuits is without adversely affecting or not adversely affecting the operation of the MR system Achieved. 2. The system of claim 1, wherein the first RF transceiver circuit comprises: (a) an RF transceiver module having an input and an output at which the physiological data from the first transducer circuit is received and at which the output transmits radio frequency sending said physiological data in (RF) form; (b) a filter connected to said output of said RF transceiver module to pass said physiological data while effectively attenuating frequencies other than those carrying said physiological data; and (c) An antenna connected to the filter for radiating the physiological data received from the filter. 3. The system of claim 2, wherein the filter is one of a band-pass filter, a high-pass filter, and a notch filter. 4. The system of claim 1, wherein the second RF transceiver circuit comprises: (a) an antenna for receiving said physiological data transmitted by said first RF transceiver circuit; (b) a filter connected to the antenna so as to pass the physiological data while effectively attenuating frequencies other than those carrying the physiological data; and (c) an RF transceiver module having an input at which the physiological data from the filter is received and an output at which the physiological data is passed to the second transducer circuit. 5. The system of claim 4, wherein the filter is one of a band-pass filter, a high-pass filter, and a notch filter. 6. The system of claim 1, wherein the second transducer circuit comprises: (a) a driver circuit having an input connected to an output of the second RF transceiver circuit; and (b) an electro-optic transducer connected to the output of the drive circuit to convert the physiological data received from the drive circuit from an electrical form to an optical form, and convert the The physiological data is communicated to the device remote from the sensor mechanism. 7. The system of claim 1, wherein said sensor mechanism is an electrocardiogram (ECG) module for acquiring said physiological data in the form of cardiac signals. 8. A system for wirelessly transmitting data in an electromagnetically noisy environment, said system comprising: (a) a first transducer circuit connected to a first device of a branching system to convert data received from the first device of the branching system from optical to electrical form ; (b) a first RF transceiver circuit connected to said first transducer circuit for transmitting said data received from said first transducer circuit; (c) a second RF transceiver circuit remote from said first RF transceiver circuit to receive said data transmitted by said first RF transceiver circuit; and (d) a second transducer circuit connected to said second RF transceiver circuit for converting said data received from said second transceiver circuit from electrical form into optical form and communicates said data to a second device of said bifurcating system; wherein the communication scheme used by said first and said second RF transceivers enables said first and said second devices to communicate without being adversely affected by said ambient noise. 9. The system of claim 8, wherein said first device of said bifurcated system includes an electrocardiogram (ECG) module for acquiring said data in the form of cardiac signals from a patient. 10. The system of claim 8, wherein said first device of said bifurcated system includes a sensor such that said data obtained thereby is indicative of a patient's condition. 11. The system of claim 8, wherein said second device of said bifurcated system includes a device capable of communicating with said first device via said second and said first RF transceiver circuitry. Communication monitoring device. 12. A system for wirelessly transmitting data in a nuclear magnetic resonance (MR) suite, said system comprising: (a) a first transceiver circuit connected to a sensor module to transmit said data received from said sensor module and to communicate to said sensor module the data transmitted to said first said data of the transceiver circuit; and (b) a second transceiver circuit connected to a monitoring device to communicate said data received from said first transceiver circuit to said monitoring device and to transfer said data received from said first transceiver circuit to said monitoring device sending said data received at the monitoring device to said first transceiver circuit; Wherein said first and said second transceiver circuits communicate by using a predetermined frequency outside the operating range of equipment in said MR suite without adversely affecting the operation of equipment in said MR suite. 13. The system of claim 12, wherein the first transceiver circuit comprises: (a) a transceiver module having an input to which the data from the sensor module is passed and an output to which the data is transmitted in radio frequency (RF) form from the The output is sent out; (b) a filter connected to said output of said transceiver module to pass said data while effectively attenuating frequencies other than those carrying said data; and (c) An antenna connected to the filter to radiate the data received from the filter. 14. The system of claim 12, wherein the second transceiver circuit comprises: (a) an antenna for receiving said data transmitted by said first transceiver circuit in radio frequency (RF); (b) a filter connected to the antenna for passing the data while effectively attenuating frequencies other than those carrying the data; and (c) a transceiver module having an input and an output at which the data from the filter is received and from which the data is passed to the monitor device. 15. The system of claim 12, wherein said data communicated by said sensor module to said first transceiver circuit includes at least one of: (i) physiological signals indicative of patient and (ii) an operational signal indicating the status of the sensor module. 16. The system of claim 15 , wherein the data communicated by the monitoring device to the second transceiver circuit includes a control signal for commanding the sensor module from multiple One or more suitable leads are selected from the set of leads from which the physiological signal can be picked up. 17. The system of claim 12, wherein the data communicated by the sensor module to the first transceiver circuit includes at least one of: (i) a cardiac signal representing a cardiac status; and (ii) an operational signal indicative of the status of the sensor module. 18. The system of claim 17, wherein the data communicated by the monitoring device to the second transceiver circuit includes a control signal for instructing the sensor module from multiple One or more suitable leads are selected from the set of leads from which the cardiac signal can be obtained. 19. A system for wirelessly transmitting data obtained from a sensor module connected to a patient located within an imaging scanner, said system comprising: (a) a first transceiver linked to said sensor module for transmitting said data received from said sensor module; and (b) a second transceiver connected to a device remote from said first transceiver for communicating said data received from said first transceiver to said device; wherein said first and said second transceivers enable said sensor module and said device to communicate without adversely affecting or adversely affecting operation of said imaging scanner communication. 20. The system of claim 19 , further comprising a first transducer circuit between said sensor module and said first transceiver for converting said sensor module optically received from said sensor module. Data is converted into electrical form for use by the first transceiver. 21. The system of claim 19 , further comprising a second transducer circuit between the second transceiver and the device for converting all the signals received electrically from the second transceiver to convert the data into a form usable by the device. 22. The system of claim 19, wherein said sensor module is an electrocardiogram (ECG) module for acquiring said data in the form of cardiac signals. 23. A method of wirelessly transmitting data representing at least a condition of a patient exposed to a magnetic resonance (MR) system scanner, said method comprising the steps of: (a) obtaining said data from a sensor mechanism coupled to said patient; (b) converting said data obtained from said patient from optical to electrical form; (c) transmit said data received electrically in radio frequency form; (d) receiving said data sent in said sending step; (e) converting said data received in said receiving step from an electrical form to an optical form; and (f) communicating said data to a device remote from said patient; Wherein the transmission of the data is realized without adversely affecting or causing adverse operation to the operation of the MR system. 24. The method of claim 23, wherein the step of obtaining said data comprises using an electrocardiogram (ECG) module in order to obtain said data in the form of heart signals. 25. A method of wirelessly transmitting data in an imaging suite, said method comprising the steps of: (a) providing a first transceiver connected to a sensor for transmitting said data received from said sensor and communicating said data transmitted to said first transceiver to said sensor; and (b) providing a second transceiver connected to a device remote from said first transceiver to communicate said data received from said first transceiver to said device, and transmitting said data received from said device to said first transceiver; Wherein said first and said second transceivers communicate without adversely affecting or adversely affecting operation of equipment within said imaging suite. 26. The method of claim 25, further comprising the step of providing a first transducer circuit between said sensor and said first transceiver for (i) optically receiving from said sensor converting said data received into electrical form for use by said first transceiver, and (ii) converting said data received in electrical form from said first transceiver into optical form for use by said first transceiver The above sensors are used. 27. The method of claim 25, further comprising the step of providing a second transducer circuit between the second transceiver and the device for (i) converting the converting said data received in electrical form into a form usable by said device, and (ii) converting said data received in optical form from said device into electrical form for reception by said second transceiver use. 28. The method of claim 25, wherein said sensor is an electrocardiogram (ECG) module for acquiring said data in the form of heart signals. 29. A communication module for wireless transmission of electrocardiogram (ECG) signals acquired from a patient located in a noisy environment, said module comprising: (a) at least one RF filter linked to the sensor of the bioelectric signal to remove frequencies other than those carrying the bioelectric signal; (b) a network that selects one or more suitable leads from a multi-lead lead set in response to a control signal to pick up a selected one or more of said bioelectrical signals from the selected leads. a bioelectrical signal; (c) a differential amplifier for deriving said ECG signal from said bioelectrical signal selected via said network; (d) amplifier circuitry for amplifying said ECG signal received from said differential amplifier; (e) signal processing circuitry for improving the condition of said ECG signal received from said amplifier circuitry; (f) a modulator circuit for digitally modulating a carrier signal based on said ECG signal received from said signal processing circuit so as to form a modulated signal; (g) a transmitter circuit connected to said modulator circuit for transmitting said modulated signal received from said modulator circuit; and (h) a filter circuit connected to the transmitter circuit so as to pass the modulated signal and effectively attenuate frequencies other than the modulated signal. 30. The communication module of claim 29, wherein the transmitter circuit transmits the modulated signal at a frequency in the microwave band. 31. The communication module of claim 29, further comprising: (a) a limiter circuit linked to the filter circuit in order to limit the amplitude of the control signal from the remote device picked up by the antenna; (b) a receiver circuit connected to the limiter circuit for receiving the control signal; and (c) an encoder circuit that encodes the ECG signal with information related to at least one of: (i) the amount of power available to the communication module; and (ii) the ECG signal is obtained from which of the leads in the multi-lead lead set. 32. The communications module of claim 29, further comprising a means for ensuring the integrity of communications between the communications module and a remote device with which it communicates. 33. A communication module for wireless transmission of physiological signals acquired from a patient located in a noisy environment, the module comprising: (a) an input conditioning circuit linked to the sensor of the physiological signal to adapt the physiological signal received from the sensor to the module; (b) signal processing circuitry for improving the condition of said physiological signal received from said input conditioning circuitry; (c) a converter circuit for converting the physiological signal received from the signal processing circuit into a digital signal corresponding thereto; (d) a transmitter circuit connected to said converter circuit for transmitting said digital signal received from said converter circuit; and (e) a filter circuit connected to the transmitter circuit to pass the digital signal and effectively attenuate frequencies other than the digital signal. 34. The communication module of claim 33 , wherein the converter circuit includes a modulator that digitizes a carrier signal based on the physiological signal received from the signal processing circuit. modulated to form the digital signal. 35. The communication module of claim 33, wherein the transmitter circuit transmits the digital signal at a frequency in the microwave band. 36. The communication module of claim 33, further comprising: (a) a limiter circuit linked to the filter circuit in order to limit the amplitude of the control signal from the remote device picked up by the antenna; (b) a receiver circuit connected to the limiter circuit for receiving the control signal; and (c) a control circuit for controlling the operation of the communication module based on a control signal received from the remote device. 37. The communication module of claim 33, wherein the control circuit is capable of encoding the physiological signal with at least information about an amount of power available to the communication module. 38. The communications module of claim 33, further comprising a means for ensuring the integrity of communications between the communications module and a remote device with which it communicates.

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